ATL97LA091 · Beech E50
Tennessee Skydiving Center Beech E50 · Accident: total loss of engine power (mechanical failure) during initial climb
From Tullahoma Regional Airport William Northern Field (THA) to an unrecorded destination
Event
- NTSB case
- ATL97LA091
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Beech E50
- Aircraft type
- Beechcraft 50
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N4265R
- Operator
- Tennessee Skydiving Center
- Onboard fatalities
- Unknown
- Route
- From Tullahoma Regional Airport William Northern Field (THA)To not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Initial climb
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Total loss of engine power (mechanical failure)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Eng assembly, crankshaft counterweights/vib damper › Failure, total
- Eng assembly, crankshaft counterweights/vib damper › Overload
- Lubricating system › Foreign material/substance
- Owner/pilot mechanic › Maintenance, service of aircraft/equipment, improper
- Unknown › Throttle/power control, improper use of
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The airplane was being used for sport parachute operations. During the initial climb after takeoff the right engine failed followed by the airplane's slow descending right turn into wooded terrain. The airplane crashed through trees and caught on fire. The fire was extinguished prior to the destruction of the airplane. Subsequent examination of the engine revealed that one crankshaft counterweight had broken its retaining lugs and was liberated inside the engine, resulting in sudden stoppage of the engine. The sudden stoppage prevented the pilot from feathering the propeller. Metallurgical examination of the crankshaft and counterweight revealed damage that was consistent with 'detuning' of the engine counterweights. Counterweight detuning results from excessively rapid throttle movements. Additionally, the engine log indicated that during an oil change 8 days before the accident, wear metal was found in the oil. The airplane continued to be flown with no further maintenance action taken.
Probable cause
improper operation of the engine that produced internal damage, and improper servicing of the airplane by the owner/pilot mechanic that resulted in the subsequent mechanical failure of the engine crankshaft counterweight. Contributing to the accident was the pilot's inability to feather the propeller.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ATL97LA091
- Event ID
- 20001208X08064
- Case number
- ATL97LA091
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 9e1ef1e6cda60bdcfd64d7a94c0f3d943a9b8374eab9cad31e2162cf7047c45e; retrieved 2026-09-21T12:00:30.764Z.